This is for everyone who has been told to "stand back please" when examining a piece of art. This month we bring you 'Easter eggs' in famous works of art - the secret bits you may have missed.

Easter eggs - unexpected or undocumented features in a piece of work - have appeared in artwork as far back as ancient societies and have been anything from a sneaky self-portrait to a UFO sighting! Here are some of the most well-known Easter eggs in art that you may have missed:

The Creation of Adam c. 1508-1512 by Michelangelo

The Creation of Adam

This renowned work from Michelangelo has graced the Sistine Chapel since 1508, and has been copied, parodied and satirised many times. But how many noticed a tribute to the artist's passion for science and the human anatomy as well as his fine painting?

It appears that God floating in his crimson pod to the right of the piece, complete with seraphim, is the exact outline of the human brain. The leg of one of the cherubs is in the correct place and shape for where the spinal chord is attached, and another's foot is in the place of the pituitary gland. The floating green scarf is even in the precise location and shape for the vertebral artery.

If that all sounds a little too much like coincidence, you may also want to know that God even extends his arm to Adam through what we now know as the prefrontal cortex. This is the part of the brain that gives humans the gift of reason and deliberation - something that sets us apart from animals. There is also a sad looking angel in the area of the brain that is activated when we experience sad emotions.

Although the discovery of the prefrontal cortex was not until the 20th century, Michelangelo had a profoundly advanced knowledge of the human anatomy due to years of dissections from the age of seventeen. But the mystery continues as dissection of the brain alone does not reveal which parts are activated for different emotions. Could this be coincidence?

With all this new information, a controversial interpretation of the art has arisen. For hundreds of years scholars believed God to be pointing at Adam as the title suggests, giving him life. After the discovery of the anatomically correct brain representation, some believe Adam is in fact pointing at God, which gives the painting an entirely different meaning. Was Michelangelo suggesting God to be a creation of the human mind? We'll never know the true answer, as none of these things were recorded by the artist. We are left to gaze and wonder...

Madonna with Saint Giovannino - Domenico Ghirlandaio

Madonna with Saint Giovannino (1449-1494)

This Italian Rennaissance artwork by Domenico Ghirlandaio is subject of much online debate. There is some speculation over who actually painted the piece, but this is not the issue that has fuelled so much debate. People are talking about the small, dark shape in the sky behind Madonna's right shoulder, which is believed by many to be a UFO. Up close, the dark shape certainly does look a little extra terrestrial and almost spaceship-like. Others have backed up this observation by adding that the lone figure in the distance and his dog are also looking up at it.

These shapes, however, are quite common in this era of artwork and were intended to resemble a gap in the heavens where divine light would shine through onto the subject in the painting. It is very much a religious trend that was around a lot in Rennaissance art. Not alien appearances.

The Mona Lisa 1503-1505 - Leonardo da Vinci

Mona Lisa

One of the most famous artworks of all time, mentioned in many conspiracy theories and books is Leondardo da Vinci's Mona Lisa. Art historians recently discovered the existence of another woman painted below the surface which raised even more questions and theories about the work. On close inspection we can also see that the artists has initialled "LV" in her right eye and the number 72 on the bridge in the background. There is also a theory that the lady in the painting is pregnant, as her arms are covering her stomach and she is wearing a veil commonly used by Italian women before and after childbirth.

The Arnolfini Portrait - Jan van Eyck

Close up of The Arnolfini Portrait Mirror

The Arnolfini Portrait

Another very famous painting from 1434 that demonstrates Jan van Eyck's meticulous brush skills in the details in the woman's dress to the right of the scene. Although it's bursting with detail for us to appreciate, there is something you may not have spotted from behind the red ropes of the National Gallery.

Look carefully at the back wall in the painting and you'll see a mirror. There are two new people painted in the reflection of the mirror, presumably the other guests in the room that we cannot see from the position the portrait was taken from! Art scholars think that one of these people may be a sneaky self-portrait of van Eyck himself, as one of the guests in the mirror has their hand held up in a gesture of greeting.

Take a look at our online gallery and see if you can spot an Easter egg in our own artists's paintings!